Matthew Osman is a geoscientist at the University of Arizona: he came to Greenland to study climate change over the past 2,000 years by extracting and analysing ice cores longer than 100 metres. The gases and chemicals housed within these cores show evidence that a thousand years ago, during the Medieval Warm Period (400 years of higher global temperatures), the ice was actually growing thicker and advancing—the opposite of what it does today. Osman’s results show that the ice cap was growing because it was warmer, as higher temperatures caused more evaporation that led to more snowfall. Whether ice grows thicker and advances depends on the balance between snowfall and how much more ice melts because of the warmer weather: during the Medieval Warm Period, summer melting did increase, but the increased snowfall won out in the end, therefore the ice kept growing. The study shows the complexity of a warming climate system, because under the right conditions it is possible to have warming and ice advance at the same time. Today, unfortunately, due to anthropogenic climate change, the ice caps and glaciers of Greenland are rapidly retreating.
Read the excellent and very interesting article by Theo Nicitopoulos, in its entirety, on Hakaimagazine